Pressure pads are used in the medical field to sense the presence of a monitored person on a surface, like a chair or a bed.
Pressure pads may be used under the mattress/cushion or on the mattress/cushion. Pressure pads located on the mattress can be exposed to bodily fluids. It is sometimes also a concern to nurse managers because of possible subtle changes in pressure on the skin, leading to decubitus ulcers.
The inventors have found that pressure switch pads known in the industry are not very reliable when used under a mattress/cushion. Variations in thickness, softness, and internal structure of the mattress/cushion result in sporadic behavior, which results in unreliable detection of the presence or absence of monitored person. One reason for this lies in the fact that basic pressure pads are created to have a specific force sensitivity, which has to be carefully selected. If the pressure pad is too sensitive, the mattress/cushion alone could trigger the pad. If the pressure pad is too lenient, the pad may not detect the presence of a light person. This is further complicated by the fact that different models of mattresses have varying masses and distributing the weight of an individual over different areas.